任意引一割线L:y-8=k(x-6),k=(y-8)/(x-6)割线L交圆于P1,P2两点k=(yP1-yP2)/(xP1-xP2)=(y-8)/(x-6)P1P2的中点P(x,y)xP1+xP2=2x,yP1+yP2=2yx^2+y^2=16(xP1)^2+(yP1)^2=16.(1)(xP2)^2+(yP2)^2=16.(2)(1)-(2):(xP1+xP2)*...